Difference Between Warm-Blooded and Cold-Blooded (With Table)

Animals are multicellular organism who belongs to the kingdom of Animalia. They are also called Metazoa or eukaryotic organisms. Animals can move freely unlike plants, can breathe, can reproduce sexually, consume organic materials and can also go into the development stage where they can evolve from cell to a blastula into a living species. On earth, there are 7 million animal species have been detected among which 1 million species are insects. Warm-blooded and Cold-Blooded Animals are also part of it.

Warm-Blooded vs Cold-Blooded

The difference between warm-blooded and cold-blooded animals is that Warm-blooded animals can maintain and regulate their body temperature irrespective of external conditions. While cold-blooded animals cannot maintain their body temperature so they have a fluctuating temperature depending upon the external environment. Warm-blooded animals need more energy so their requirement for food is higher. Cold-blooded animals require less energy so the requirement for food is lower.

Warm-Blooded Animals are also called Endothermic animals because they can regulate their body temperature irrespective of the external environment. Such animals try to increase their metabolism by consuming more food which in turn increases the heat of the body. Most common examples of warm-blooded animals are birds, mammals, fish etc. Warm-blooded can be divided into three broad categories i.e. Endothermy, Homeothermy and Tachymetabolism.

Cold-Blooded Animals are also called exothermic animals because they have a fluctuating temperature and are not able to regulate the temperature of their body. They are dependent on external sources to provide them heat such as sunlight. So such animals require very less amount of energy, hence they consume very little food. Examples of cold-blooded animals are reptiles, amphibians, invertebrates. Cold-Blooded can be divided into three broad categories i.e. Ectothermy, Poikilothermy, Bradymetabolism.

Comparison Table Between Warm-Blooded and Cold-Blooded

Parameters of ComparisonWarm-BloodedCold-Blooded
EnergyMore energyLess energy
MetabolismDoesn’t changeChanges with the environment.
PhaseNo phaseHibernation and Aestivation
TemperatureRanges between 35-40 degrees Celsius.Changes with the external environment.
SurvivalEasily adaptable to any kind of environment.Cannot survive in extreme temperatures.
FeatureHave a strong immune system.Resistance to microorganisms.

What is Warm-Blooded?

Warm-blooded animals have a system of internal mechanisms which helps them to survive in any kind of temperature and environment. If there is a warm temperature outside then their body will cool down and if there is a cold temperature outside then their body will warm up by regulating the metabolic rate of the body. The warm-blooded temperature remains the same if they are moving from one place to another. Because of this, their body needs a lot of energy and the demand for food is higher.

Temperature in their body ranges between 35-40 degrees celsius. It includes birds, fish and mammals. Mammals and birds are called homeothermic animals. Because they have different methods for thermoregulation i.e. endothermy and homeothermy. Warm-blooded is a very broad category to define. So it is divided into three to make the classification easier. They are endothermic, homeothermic, and tachymetabolic. Most warm-blooded use the combination of endothermy and homeothermy.

Endothermy is a process through which animals control the temperature of their body by burning fat, shivering, and panting. Homeothery is a process where the constant temperature of the body is maintained by the animals irrespective of changing external environment. Warm-blooded also have a defence mechanism against fungal infections. Very few fungi can enter and survive the body temperature. Similarly warm-blooded also have a defence against pathogens. They have a very strong immune system that doesn’t allow anybody to enter.

What is Cold-Blooded?

Temperature of the cold-blooded animals fluctuates as they keep moving into different surroundings. As they are dependant on external sources for warmth and heat such as sunlight i.e. they cannot survive in extreme temperatures especially during the cold. Their body temperatures constantly change because of the external environment. As they cannot produce heat in the body they require very little energy for the regulation of temperature. Consumption of food by cold-blooded is also very less.

Cold-blooded hibernates during the winter period. They remain inactive. Examples of cold-blooded are fish, reptiles and invertebrates. Fish goes into the deeper part of the sea and ocean during the winter period. Because they may die. Snakes, frogs, crocodiles hibernate to save energy. Cold-blooded uses three types of mechanisms for thermoregulation i.e. Poikilothermy, Ectothermy, or Heterothermy.

Ectothermy is a process where cold-blooded utilizes external means like sunlight to regulate body temperature. Heterothjermy is a mechanism where the temperature of cold-blooded may change drastically while moving. Poikilothjermy is a process where the core temperature of cold-blooded remains the same but the internal temperature may vary due to the environment. Cold-blooded has resistance towards diseases. They do not allow harmful microorganisms and parasites. If it enters the body and catches a disease then they lower the body temperature to get rid of it.

Main Differences Between Warm-Blooded and Cold-Blooded

  1. Warm-blooded requires more energy to regulate and control body temperatures. Cold-blooded requires less energy to regulate and control body temperatures.
  2. Metabolism of warm-blooded doesn’t change with surroundings and environment. Metabolism of Cold-blooded changes with the environment.
  3. Warm-blooded undergoes no phases like cold-blooded. Cold-blooded undergoes two phases i.e. Hibernation and Aestivation.
  4. Temperature of warm-blooded ranges between 35-40 degrees Celsius. Temperature of cold-blooded changes with the external environment.
  5. Warm-blooded are easily adaptable to any kind of environment. Cold-blooded cannot survive in extreme temperatures especially during cold.
  6. Warm-blooded Have a strong immune system. Cold-blooded have resistance to microorganisms.


Both warm-blooded and cold-blooded animals are found in the environment. Both have their mechanism and metabolism to maintain and regulate the temperatures. Both try to regulate the heat in their body by different methods. Warm-blooded have a very complex system in their body. Cold-blooded do not have such complex systems. Cold-blooded have various proteins which work on different levels concerning the external environment. Genomes found in cold-blooded are very complex. While genome in warm-blooded animals is simpler. Fat plays a very important role for warm-blooded animals, especially for seals and whales. Excessive fat in a cold-blooded animal leads to overheating of their bodies and eventually death.


  1. https://journals.physiology.org/doi/pdf/10.1152/ajplegacy.1951.166.1.92
  2. https://books.google.com/books?hl=en&lr=&id=8N2kGv3LoOUC&oi=fnd&pg=PA187&dq=Warm-Blooded+and+Cold-Blooded&ots=vihgCXcLez&sig=d1flPmxm2FlNm7juzzfLjvwj4No
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